Just use a standard USB WIFI Adapter. They work fine for windows 8 or 10. Plug and play. $22
It's likely any pcie (pci express) wifi card will work for you. Even older pci cards, if your 990 has a pci slot. Look on ebay, there are many for sale, new and used. It need not be a dell branded part.
I have a cheap usb dongle, and it works fine when I need wifi, but I generally use an ethernet connection.
You'll have to do your own investigation regarding speed and range, if these are critical parameters in your application.